What is the Big Bang? | Astronomy Essentials

What is the Big Bang? | Astronomy Essentials 

        There’s no better place to start out considering the broad sweep of astronomical history than the beginning—that is, the particular beginning of both space and time. Twentieth-century astronomers like Edwin Hubble discovered that the universe is expanding by observing that large-scale structures like galaxies are all moving faraway from one another , in any direction that we glance . this suggests that, in the past, the universe was smaller which , at some point within the far distant past, everything began as one point of space and time: a singularity. Years of careful observations by the Hubble Space Telescope and other facilities have revealed that the universe was born during a violent explosion of this singularity about 13.7 billion years ago.

       The details of big bang theory—as it had been initially dubbed by astronomers in the 1930s—have been rigorously tested with decades of astronomical observations, laboratory experiments, and mathematical modeling by cosmologists and astronomers who specifically focus their research on the origin and evolution of the universe. What we've learned about the first history of our universe from these studies is impressive: within the primary second of the universe’s presence, the temperature dropped from a million billion degrees to “just” 10 billion degrees, and every one of the universe’s present supply of protons (hydrogen atoms) and neutrons formed out of this primordial plasma. By the time the universe was only three minutes old, helium and other light elements had been formed from hydrogen within the same quite fusion process thatstill occurs today deep inside stars. 

       This is mind-blowing to believe both space and nonce created at one instant, 13.7 billion years ago. What caused the explosion? What was there before the big bang? Cosmologists tell us that we can’t really ask that question because time itself was created within the explosion . It’s also humbling to understand that the most abundant element within each of our bodies—hydrogen—was created in the very first second that ever was. We are ancient!